The trend in the circuit protection industry is currently toward complete circuit protection which is accomplished by the addition of supplemental protection apparatus to standard overcurrent protective devices, such as molded case circuit breakers. In the past, when such auxiliary protection apparatus or other circuit breaker accessories were combined with a standard circuit breaker, the accessories were usually custom-installed at the point of manufacture. The combined protective device, when later installed in the field, could not be externally accessed for inspection, replacement or repair without destroying the integrity of the circuit breaker interior. U.S. Pat. No. 4,894,631 describes a molded case circuit breaker containing an actuator-accessory unit which provides a wide variety of circuit protection accessory options. This patent is incorporated herein for purposes of reference and should be reviewed for its description of the state-of-the-art of such circuit breakers and accessory devices.
U.S. Pat. No. 4,913,503 describes a reset mechanism for a lower ampere-rated circuit interrupter usually employed as a "branch" circuit interrupter within industrial power distribution systems downstream from a higher-rated "main" circuit interrupter. When electronic trip units are used within the higher-rated circuits, a "flux shifter" tripping device is used to articulate the interrupter operating mechanism upon overcurrent conditions. One such flux shifter device is described within U.S. Pat. No. 4,641,117 which Patent is incorporated herein for purposes of reference. With the heavier operating mechanism springs used within higher-rated circuit interrupters, the actuator-accessory unit, per se, is incapable of generating sufficient tripping force to articulate the operating mechanism, such that additional tripping force is required. The additional tripping force is provided by a supplemental tripping mechanism which interacts with the actuator-accessory unit through a sequential resetting arrangement to insure that the actuator-accessory unit becomes reset before the main operating mechanism is reset. The operation of the sequential latching arrangement is described within U.S. patent application Ser. No. 518,672 filed May 3, 1990 entitled "Actuator-Accessory Reset Arrangement for Molded Case Interrupter or Electric Switch" which Application is incorporated herein for purposes of reference.
One purpose of this invention is to describe the supplemental tripping mechanism and its interaction with the sequential latching arrangement to interrupt circuit current by direct operation of the actuator-accessory unit.